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Ch.1 - Introduction: Matter, Energy, and Measurement
Chapter 1, Problem 4d

Consider the two spheres shown here, one made of silver and the other of aluminum. (d) If you release the spheres simultaneously, they will have the same velocity when they hit the ground. Will they have the same kinetic energy? If not, which sphere will have more kinetic energy?

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Kinetic Energy

Kinetic energy is the energy an object possesses due to its motion, calculated using the formula KE = 1/2 mv², where m is mass and v is velocity. Although both spheres will have the same velocity upon hitting the ground, their kinetic energies will differ because kinetic energy is also dependent on mass.
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Mass and Weight

Mass is a measure of the amount of matter in an object, while weight is the force exerted by gravity on that mass. In this scenario, the silver sphere has a greater mass than the aluminum sphere, which means it will have a higher weight and, consequently, more kinetic energy when both are dropped from the same height.
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Acceleration due to Gravity

Acceleration due to gravity is a constant value (approximately 9.81 m/s² on Earth) that affects all objects regardless of their mass. When both spheres are released, they accelerate towards the ground at the same rate, ensuring they reach the same velocity just before impact, but this does not influence their kinetic energy, which is also dependent on their respective masses.
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